Metallic shotshell



Sept. 2,

M. L- ROBINSON ETAL METALLIC SHOTSHELL Filed July 27, 1956 INVENTORS. MERTON L. ROBI NSON JAMES G. BAKER ATTOR NEY NIETALLIC SHOTSHELL Merton L. Robinson, Woodbridge, and James G. Baker,

Hamden, Conn., assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia Application July 27, 1956, Serial No. 600,519

1 Claim. (Cl. 102-42) This invention relates to shotshells and in particular to thin-walled metallic shotshells.

One of the chief difliculties which is encountered in the use of thin-walled metallic shotshells is the occurrence of cut-offs. In the art to which this invention pertains, the term cut-off defines the development of a partial or a complete separation between the cylindrical portion of the shotshell and the head or primer end of the shell upon firing. Such a shell failure is undesirable for several reasons. For example, a partial or a complete cut-off will permit hot, high pressure gases to escape from the chamber endangering the operator of the gun. Furthermore, a ruptured shell is difficult if not impossible to extract.

The cut-01f problem is particularly bothersome in the use of thin-walled metallic shells having wall thicknesses of the order of .020 thousandths of an inch or less.

Frequently it is desirable to fabricate metallic shells from materials which are susceptible to hardening. For example, shotshells made of aluminum are heat treated to develop desirable hardness and tensile characteristics so as to withstand ordinary handling without marring or scoring and to facilitate loading and ejecting. Aluminum shotshells which exhibit good handling characteristics as a result of hardening frequently exhibit low elongation properties such that upon firing within the chamber of a shotgun, there is a separation or a cut-off between the head of the shell and the main body thereof.

Accordingly, it is a particular object of the present invention to provide a new and improved metallic shotshell.

Another object of the present invention is to provide a new and improved aluminum shotshell.

A still further object of the present invention is to provide a thin-walled metallic shotshell which is not susceptible to cut-offs.

A still further object of the present invention is to provide an aluminum shotshell having an improved base wad.

A metallic shotshell embodying certain features of the present invention may comprise a tubular member having one end substantially closed, a base wad disposed within the tubular member and positioned adjacent the closed end, said base wad having a diameter at the end thereof nearest said closed end which is substantially smaller than the diameter of the opposite end of the wad so as to create a circumferential void about the wad.

' A complete understanding of the present invention may be obtained from the following detailed description of a shotshell constituting a specific embodiment thereof, when read in conjunction With the appended drawing in which;

Fig. 1 is an elevational view, partially in section, of a metallic shotshell having a conventional or prior art base wad structure;

Fig. 2 is a view similar to Fig. l and illustrates an aluminum shotshell embodying the present invention 2,849,954 Patented Sept. 2, 1958 wherein the base wad is tapered downwardly and inwardly.

Fig. 3 is a sectional view of a portion of the shotshell of Fig. 1 showing the area of application of thrust upon the head of the shell and the location of a typical separation or cut-01f" occurring between the head and the side wall of a prior art shell; and,

Fig. 4 is a view similar to Fig. 3 showing the focal point of thrust in an aluminum shotshell utilizing the tapered wad of the present invention.

Referring now in detail to the drawing and in particular to Fig. 1, there is shown a prior art aluminum shotshell indicated generally by the reference numeral 10. The shell comprises a side-wall portion 11 with integral head 12 and is formed with an inwardly turned crimp 13. Disposed within the shell and immediately adjacent the head 12 is a base wad 15. The wad 15 is generally representative of prior art base wads, usually formed of paper, whose performance has been found unsatisfactory in combination with metallic shotshells.

The base wad 15 is formed with a central aperture 14 for receiving a primer assembly 16 of conventional arrangement. The base wad 15 is further formed with a flange 20 which serves to rivet or secure an overlay wad 25 to the base wad. The overlay wad 25 is generally cup-shaped and acts to make a gas-tight seal between the interior of the side-wall 11 and the exterior of the base wad as at 26. A powder charge 17 is positioned immediately above the overlay base wad assembly. Suitable wads 18 are disposed between the powder charge and a shot column 19. A closure is accomplished by securing a top wad 21 between the crimp 13 and the shot column, or a folded type crimp without top wad may be applied.

At this point, it is well to note that in firing a metallic shell such as the aluminum shotshell 10 of the general configuration shown in Fig. 1 in a commercially available shotgun, it has been found that there is such severe thrust upon the head 12 of the shell in a direction shown by the arrows of Fig. 3 that a separation or a cut-off frequently occurs. For example, the head portion 12 partially or completely separates from the side wall 11 leaving a gap as shown at 22 in Fig. 3, which may extend around the full periphery of the casing.

Although the cause for cut-oifs in metallic shotshells is not completely understood, one explanation advanced is that during detonation of the shotshell within the chamber of a shotgun the side wall 11 of the shell is forced outwardly by explosive gases against the interior walls of the chamber to the extent that side wall of the shell momentarily seizes the chamber. Simultaneously, there is a rearward thrust in the direction of the arrows of Fig. 3 which drives the head 12 to the rear taking up head space, temporary yield, or other play frequently found in the breech of a conventional shotgun. Since the side wall 11 is momentarily seized against the chamber, while a rearward thrust is being applied against the head of the shell, a separation, as shown at 22, frequently occurs. The amount of play is often as much as .035 thousandths of an inch and in cases where the metallic shell has very little ability to elongate the cut-off problem is very serious.

Referring now to Figs. 2 and 4, it is noted that the present invention contemplates a metallic shell such as an aluminum shotshell generally similar to the shotshell of Figs. 1 and 3 with the exception that a base wad 150 is provided having a downwardly and inwardly tapered configuration with respect to the head of the shell 120. The wad is constructed of a generally rigid material capable of retaining its shape under firing pressure. The shell 100 has a side wall having a thickness of approximately .011 thousandths of an inch and the "head 120ha's aw'all thickness of approximately .038 thousandths of an inch. 'Itis netintended thatthe shell be limited to the above-noted wall thickness; the figures are noted primarily for purposes of illustration of a particular emb'odiinent'of the invention. 'lnalloth'e'r respects the interior elements of the shell 100 are generally 'si'r'niiar to correspondin elements "at the shell "(if Fig. 1.

Since the present invention "is directed to the "base wail 1'50 and to the combination or the base wad "150 with a "thin walle'd metallic sh'o't's hell such as the aluminum shell 100, it is net'deemed neee's sary to describe the other elements of the 'hell 'in -detail other than to state that it is contemplated that ashbtshell embodying the principles of the present'inventien-rnay ihclifde, 'ameng other elements, a primer assembly 160, an'overlay'wad 250sec1'1rizd by a flange '2'00 integral'with "the bese'wa'd, a powder charge 170,end a 'sho't'colu'm'n '190.

Referring now to Fig. '4, it i ap arent that the ngicl tapered wad 156 is formed with a fr'n'st'oeeni'c section 131 and a central aperture 132. By virtue of '-this 'arrangement, the thrust resulting from "the detonation of a'shell is directed "inwardly towards the center "of the head 120 and is distributed about an area defining an annulus 121. Theeffect of thus concentrating'the rearwardly directed thrust is to cause the head 120 to bow outwardly at the moment 'of detonation to a position shown in exaggerated fashion by the dotted lineat '122 Concentratio'n'of the thrust load upon the center of head 120 and the'att'endant bowing of the center of the head satisfies the tendency for the head to 'take up the play in'the breechat firing. Movement of the rim portion 122A "ofth'e head is substantially reduced with the result that cut-offs between the head no and the side wall 110 are eliminated.

Note that the cylindrical portion 133 of the wad makes a snug fit with the interior of the 'side wall 110 and that a -gas seal for preventing the "How of gas into the annular void 134 is provided by the overlay wad 250. The overlay is held in .place, "of course, by the collar 200 formed integral with the bas'ewad; the collar 200 is used to rivet the overlay wad in place.

As stated before, utilization of the tapered base wad has overcome the cut-ofiproblem in shotguns having play or head space in the breech mechanism of as much as .035 thousandths of an inch.

It is not intended that'the present invention be, limited to aluminum shells and it is Within the contemplation of the present invention to utilize shotshells formed of any suitable metallic material such as brass, steel, alumin'u'r'n alloys, titaniumandthe like. The base wad may be formed of any suifable material such a's-pol'y'ethylene, nylon, paper, including paper'er-cldth impregnated with plastic which is sufliciently rigid to resist deformation under firing pressure.

It is anticipated that various arrangements and modifications of the present invention may be devised without a departure from the spirit and scope of the present invention. v

In a metallic shotshell -having-a headportion formed integral with a tubular "body ..portion, said head portion beingfcirmeil with a generally ilat interior surface definingenannnlns neans incllu'di'ng atgas sealing cup-shaped e vetl'ay 'Wad arid an interlocked "base wad for preventing physical separatib'n off'thI'e 5 head and body portions upon firing, said base wad being formed with'an exterior taper tl part extending 'albng'more than one-half of its height, the "remaifiin'g fp'art (if said wad-snugly engaging the-injterioref said tubular body portion, said base wad engaging thjea: lu's where'hy circumferential, annular v'oidisprovid'ed" 1thinthefshell in the area of the junction of the head .portion'and'tiibular"bodyflportion of the shotshell, said "eve laywad and "said base wad cooperating to prevent the u'eveleprnent (if iluid' pressure withinsaid v'oi utterances-three tn' the Tire "of this patent I FoiiEIGN J ATENTS veneer-mama'- 

